I have now found that although neither Google Chrome nor Microsoft Edge displayed a panel such as the one that Marydoll posted, they did each notify Not secure but only in small type to the left of the web address of the page. I had not noticed that.
The issue appears to be that the Not secure message does not necessarily mean that there is anything wrong with the information in the website, it appears to refer to the fact that the information flow between the person using the website and the computer that hosts the website is unencrypted, so someone could be eavesdropping on the information and recording it and using it for some purpose.
So if, for example, it is a website such as a bank and the user was using internet banking and the site was not https, this could be a big security risk.
It is interesting that the website of the Ileostomy Association itself is https but upon entering the forum from that website, the forum is http and thus flagged as not secure. I don't know why, maybe the software that supports the forum does not have https capability, or some other reason.
It seems to me that the situation is similar to someone in everyday life potentially overhearing a conversation - if the discussion is on private matters then a big issue, but if the conversation is something like asking for how much a can of baked beans costs, then not so bad, thiugh the person does learn that the person is interested in knowing the cost of a can of baked beans.
Anyway, I just wanted to post this note for completeness.